adevctl – Control the default audio sink/source devices

adevctl

#!/usr/bin/env bash

set -euo pipefail

declare _OPTION_SOURCE=false
declare _OPTION_SINK=false

_optparse() {
  while getopts "sSh" opt; do
    case "$opt" in
      s)
        _OPTION_SINK=true
        ;;
      S)
        _OPTION_SOURCE=true
        ;;
      h)
        print_help
        exit 0
        ;;
      *)
        print_help >&2
        fatal "Unknown flag: $opt"
        ;;
    esac
  done
}

print_help() {
  echo "Control the default audio sink/source devices"
  echo "Usage: adevctl [-s|-S|-h]"
}

fatal() {
  echo "Error: $*" >&2
  exit 1
}

list_devices() {
  local dev_type=$1

  #shellcheck disable=SC2016
  local awk_query='$1=="factory.name" && $3=="\"api.alsa.pcm.'"$dev_type"'\"" {found=1; next} found && $1=="node.name" {found=0; gsub("\"", "", $3); print $3}'

  pactl list \
    | awk "$awk_query" \
    | sort -u
}

get_default_device() {
  local dev_type=$1
  pactl "get-default-$dev_type"
}

get_next_device() {
  local current_dev="$1"; shift
  local -a devs=("$@")
  local dev next_dev

  for idx in "${!devs[@]}"; do
    dev="${devs[$idx]}"

    if [[ "$dev" != "$current_dev" ]]; then
      continue
    fi

    # If the last dev is selected,
    # the next dev is the first one.
    if (( idx >= ${#devs[@]}-1 )); then
      next_dev="${devs[0]}"
    else
      next_dev="${devs[$idx+1]}"
    fi
  done

  if [[ -z "$next_dev" ]]; then
    fatal "couldn't find the next device to switch to"
  fi

  echo "$next_dev"
}

set_device() {
  local dev_type=$1; dev=$2

  pactl "set-default-$dev_type" "$dev"
  notify_new_device "$dev_type" "$dev"
}

notify_new_device() {
  local dev_type=$1; dev=$2

  if command -v notify-send &> /dev/null ; then
    notify-send -u low -t 3000 "Default audio $dev_type: $dev"
  fi
}

print_current_devs() {
  echo "sink: $(get_default_device sink)"
  echo "source: $(get_default_device source)"
}

main() {
  local -a devs current_dev next_dev dev_type=""

  _optparse "$@"

  if [[ "$_OPTION_SINK" == true ]]; then
    dev_type=sink
  elif [[ "$_OPTION_SOURCE" == true ]]; then
    dev_type=source
  fi

  if [[ -z "$dev_type" ]]; then
    print_current_devs
    exit 0
  fi

  mapfile -t devs < <(list_devices "$dev_type")
  current_dev="$(get_default_device "$dev_type")"
  next_dev="$(get_next_device "$current_dev" "${devs[@]}")"

  set_device "$dev_type" "$next_dev"
}

main "$@"